Clarence House has now confirmed that Camilla has a prior engagement near her Scottish home Birkhall, believed to have been arranged before the date for the nuptials was announced.

The 71-year-old, who is known as the Duchess of Rothesay in Scotland, will carry out engagements in Aberdeenshire on 11 and 12 October.

Over the two days, she will visit Alford Community Campus, where she will join a cookery class and watch a Harvest Festival performance from local primary school pupils.

Camilla will also take a trip to Crathie Primary School to see displays created by the children in celebration of the Cairngorms (Scottish mountain range) and The Duke of Rothesay Highland Games Pavilion in Braemar, which was opened by the Queen last month.

The Duchess is expected to be the only senior member of the royal family to miss the ceremony at St George’s Chapel in Windsor.

The Duke of Kent will also not be attending the ceremony on Friday. The Queen’s cousin has a prior engagement at the Military Rehabilitation Headley Court Gala Dinner in London.